The present invention relates to an improved apparatus for conditioning air for a vehicle compartment with a higher air cooling capability.
Japanese Patent Application first Publications (Tokkai) sho No. 60-61326 and sho No. 60-244612 exemplify structures of the air conditioning apparatuses.
One of the previously proposed air conditioning apparata disclosed in the above-identified earlier Japanese Patent Application document will be described below.
A passage of air stream is formed in a heating unit casing. The air stream passage is extended from an air intake opening of the heating unit casing to an air blow-out opening thereof. In the air stream passage of the air conditioning apparatus, a blower, an evaporator, an air mixing door, and a heater core are disposed sequentially with respect to the direction of the air stream. The heater core serves to partition the air stream passage into two parallel branch passages; a first air stream passage for introducing air to the heater core and a second air stream passage for mixing air. The first air stream passage is defined by a wall of the heating unit casing opposing the heater core and air introducing side of the heater core. The heater core is disposed in the heating unit casing so that a downstream of the second air stream passage is wider in cross sectional area than an upstream thereof. Therefore, the heater core is inclined with respect to the air stream passage.
In addition, the air mixing door is attached to the casing, with a pivotal axle thereof being disposed at a corner between an air introducing side surface of the heater core and upstream side end surface. An opening angle of the air mixing door with respect to the heater core is adjusted to provide temperature adjustment of blowout air of the air conditioning apparatus, changing a mixture ratio of cooled air and warmed air in the blow-out air from the blowout air opening. When the air mixing door completely closes the first air stream passage for the heater core, a maximum cooling state is set. When the air mixing door completely opens the first air stream passage for the heater core, a maximum heating state is set.
However, in general cooling capability of air conditioning apparatuses tends to be inferior to heating capability in air conditioning apparatuses applied to automotive vehicles. This is because the compressor and condensor of the air conditioning apparatus tend to become small-sized due to a limited space for mounting one air conditioning apparatus on the vehicle body and a lower suppressed driving force required to operate the air conditioning apparatus.
Next, the following problems arise in a maximum cooling operation mode of the previously proposed air conditioning apparatus in which a maximum cooling capability thereof is exhibited.
(1) The air mixing door is disposed on a corner between the air introduction side surface of the heater core and the upstream side end surface of the heater core so as to expose the upstream side end surface to the air stream when the air mixing door is completely closed to block the first air stream passage. Thus, an airflow speed in the second air stream passage becomes lowered due to an air resistance of the upstream side end surface of the heater core against the air stream and accordingly air flow quantity supplied to the vehicle compartment becomes reduced. Consequently, the vehicle compartment is not quickly cooled. In addition, noise is generated in the second air stream passage when the air stream passes aside the upstream side end surface of the heater core.
Such a problem is common in any of the air conditioning apparatuses in which the upstream side end surface of the heater core is exposed to the air stream.
(2) Since the heater core is disposed so that the downstream side of the second air stream passage becomes wider, a part in which air stream pressure becomes negative occurs and unfavorable turbulence is generated therein. Consequently, airflow speed becomes slow and accordingly airflow quantity becomes reduced. In addition, undesirable turbulence noise is generated in the maximum cooling operation mode of the air conditioning apparatus.
In the way described above, the cooling characteristic of the air conditioning apparatus becomes reduced. The same problems apply equally well to the air conditioning apparatus disclosed in the above-identified latter Japanese Patent Application document.